[PATCH] Fold (a > 0 ? 1.0 : -1.0) into copysign (1.0, a) and a * copysign (1.0, a) into abs(a)

[Andrew Pinski <pinskia at gmail dot com>]

Hi,
  I decided to split my previous patch into two different patches, one
for floating point and one for integer.  This is the floating point
version as we can use copysign here which should allow for more cases
to be optimized and even by a phiopt which uses match-and-simplify (I
hope to be able to submit that during stage 1).

This patch adds the following transformations:
Transform (X > 0.0 ? 1.0 : -1.0) into copysign(1, X).
Transform (X >= 0.0 ? 1.0 : -1.0) into copysign(1, X).
Transform (X < 0.0 ? 1.0 : -1.0) into copysign(1,-X).
Transform (X <= 0.0 ? 1.0 : -1.0) into copysign(1,-X).
Transform (X > 0.0 ? -1.0 : 1.0) into copysign(1,-X).
Transform (X >= 0.0 ? -1.0 : 1.0) into copysign(1,-X).
Transform (X < 0.0 ? -1.0 : 1.0) into copysign(1,X).
Transform (X <= 0.0 ? -1.0 : 1.0) into copysign(1,X).

Transform X * copysign (1.0, X) into abs(X).
Transform X * copysign (1.0, -X) into -abs(X).

Transform copysign (-1.0, X) into copysign (1.0, X).

The last one is there so if someone decides to writes -1.0 instead of
1.0 in the code we would get the optimization still.

OK?  Bootstrapped and tested on aarch64-linux-gnu with no regressions.

Thanks,
Andrew Pinski

ChangeLog:
* match.pd (X >/>=/</<= 0 ? 1.0 : -1.0): New patterns.
(X * copysign (1.0, X)): New pattern.
(X * copysign (1.0, -X)): New pattern.
(copysign (-1.0, X)): New pattern.

testsuite/ChangeLog:
* gcc.dg/tree-ssa/copy-sign-1.c: New testcase.
* gcc.dg/tree-ssa/copy-sign-2.c: New testcase.
* gcc.dg/tree-ssa/mult-abs-2.c: New testcase.

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